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VW Polo 3cyl - small fix, big fix, or petrol + match?

  • 03-05-2016 09:32AM
    #1
    Special Circumstances
    Closed Accounts Posts: 7,569 ✭✭✭


    Had my chinese diagnostics unit with me over the weekend and scanned the following codes on a very rough running Polo 9n:

    16804 - Catalyst efficiency below threshold, intermittent
    16687 - Cylinder 3 misfire, intermittent
    16556 - System too rich (bank1), intermittent
    16825 - Tank venting system, incorrect flow. (weird one - Evap emissions problem?)
    Idles like cr@p. Like 2 cylinders. Smooths out fine when revved...is this the dreaded polo "exhaust valve forked", or something less serious?

    Also:
    00532 - Airbag voltage supply,0, intermittent.
    01598 - Central Electronics, Battery voltage,0, intermittent.
    Third brake light permanently on.
    Does the zero in the faults above suggest an earth fault or a +ve voltage too low problem?


    So...
    Small fix - plugs and coils and clear faults, see what comes back?
    Big fix - Head off, new valve cyl3, Cat? (spurious? used genuine? new genuine?) plugs, coils. Anything else you'd roll in there while things were apart?

    Any idea of costs for the big fix... or is it gallon of petrol and a match job?
    Very tidy car otherwise.



    Impressed with the software - "treble speaker front left open circuit" was a surprising level of detail on a ten year old passat. I wish the other error codes on it were as clear :-(


Comments

  • #2
    Special Circumstances
    Closed Accounts Posts: 7,569 ✭✭✭Special Circumstances


    Surprising that no one has experience of this. Maybe most people on here only have VWs during the warranty period. Probably a good idea!


  • #3
    George Dalton
    Registered Users, Registered Users 2 Posts: 5,728 ✭✭✭George Dalton


    It's impossible to put a price on it.

    A bad coilpack is the most likely scenario. Swap coilpack 3 onto a different cylinder, clear the codes and run the engine until it logs a misfire code again. If the misfire code has moved with the coilpack then you know you have found the problem. Otherwise you could be into a very large repair bill.

    Genuine VW coilpacks aren't much more expensive than aftermarket and last a lot longer.


  • #4
    jimgoose
    Registered Users, Registered Users 2 Posts: 20,196 ✭✭✭✭jimgoose


    Seems burned exhaust valves are common on those things. Did you do the old piece of paper against the tailpipe trick to check for any suck-back? It might also be worth cleaning the throttle-body and forcing the EGR to stay closed, if present, for a while to see if that improves things. The fact that the running smoothens out with some revs is encouraging anyway, I think.


  • #5
    irish bloke
    Registered Users, Registered Users 2 Posts: 2,057 ✭✭✭irish bloke


    Anytime I have had a coil pack down (and that's many times) the system always generates several unrelated faults, some similar to what you have.

    Swapping to coil pack as suggested and clearing codes is good advice


  • #6
    jca
    Closed Accounts Posts: 8,585 ✭✭✭jca


    A compression test would tell a lot too.


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  • #7
    Special Circumstances
    Closed Accounts Posts: 7,569 ✭✭✭Special Circumstances


    I've heard it's well bollixed. Local VW garage say 2k to fix.

    Would an indy bring it in at 1k worst case?

    I assume trying to source a decent replacement engine is a futile exercise?


  • #8
    jca
    Closed Accounts Posts: 8,585 ✭✭✭jca


    Special Circumstances wrote: »
    I've heard it's well bollixed. Local VW garage say 2k to fix.

    Would an indy bring it in at 1k worst case?

    I assume trying to source a decent replacement engine is a futile exercise?

    Engines are around, a friend of mine went down the repair route initially (05 Polo bought new) but it ended in disaster. He sourced an engine from a 09 car and it's flying it now.


  • #9
    jimgoose
    Registered Users, Registered Users 2 Posts: 20,196 ✭✭✭✭jimgoose


    Special Circumstances wrote: »
    I've heard it's well bollixed. Local VW garage say 2k to fix...

    So what's actually up with it - burnt valve?


  • #10
    Special Circumstances
    Closed Accounts Posts: 7,569 ✭✭✭Special Circumstances


    jimgoose wrote: »
    So what's actually up with it - burnt valve?
    Various Warnings. Very W@nked. Voluminous Wallet needed.

    Naw, that's obviously a dealer figure involving a brand new OEM cat, head off valve done... is it only the one valve that goes? Do they roll in a new timing chain or tensioner while they are at Das?

    It's this kinda craic makes me wonder about the awful rep Corsas have on here - buy a Polo they said, be grand they said!


  • #11
    jimgoose
    Registered Users, Registered Users 2 Posts: 20,196 ✭✭✭✭jimgoose


    Special Circumstances wrote: »
    ...It's this kinda craic makes me wonder about the awful rep Corsas have on here - buy a Polo they said, be grand they said!

    Those small Polo engines are soft enough. Apparently the valve-stem guides wear and let the valve move side-to-side enough to let exhaust gas howl past and burn them to buggeration. To make matters worse they tend to be bought by youngsters who can't insure anything else, who then proceed to rag them up the N24 at 80 mph and they're not able for it, so a lot of the used engines you'll encounter are fucked as well. The CBR250RR had much the same issue. :pac:


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  • #12
    jca
    Closed Accounts Posts: 8,585 ✭✭✭jca


    LIGHTNING wrote: »
    My mechanic mate warned me in regard to Polo's replacement engines. He had one brought to him (Against his advice) and the replacement was in worse shape than the one that was in the car.

    Those are the risks you take I suppose. My friend got the head done on his but it still was failing on emissions. He then got a new cat, still the ****er failed. All through this lengthy saga while driving with no nct it was burning oil at an increasingly rapid rate. The guy who sourced the 09 engine for him knew the car it came from and was very confident it was good. It's being going very well for him so far.


  • #13
    jca
    Closed Accounts Posts: 8,585 ✭✭✭jca


    jimgoose wrote: »
    Those small Polo engines are soft enough. Apparently the valve-stem guides wear and let the valve move side-to-side enough to let exhaust gas howl past and burn them to buggeration. To make matters worse they tend to be bought by youngsters who can't insure anything else, who then proceed to rag them up the N24 at 80 mph and they're not able for it, so a lot of the used engines you'll encounter are fucked as well. The CBR250RR had much the same issue. :pac:

    I think the opposite was the problem with the Polo engine. People buying them and then only tootling around town for weeks on end caused carbon to build up behind the exhaust valves preventing them from closing properly (no3 in particular) we all know what happened next.


  • #14
    Special Circumstances
    Closed Accounts Posts: 7,569 ✭✭✭Special Circumstances


    jca wrote: »
    I think the opposite was the problem with the Polo engine. People buying them and then only tootling around town for weeks on end caused carbon to build up behind the exhaust valves preventing them from closing properly (no3 in particular) we all know what happened next.

    It's a thermal problem from what I've gathered? Valve was not made of the right material to suit the 3cyl engine running a bit rich? Meh either way...

    Sucks for the youngfella that owns it though.


  • #15
    jca
    Closed Accounts Posts: 8,585 ✭✭✭jca


    Special Circumstances wrote: »
    It's a thermal problem from what I've gathered? Valve was not made of the right material to suit the 3cyl engine running a bit rich? Meh either way...

    Sucks for the youngfella that owns it though.

    Sure does. Between the two engines my friend was stung to the guts of €1500!!


  • #16
    Special Circumstances
    Closed Accounts Posts: 7,569 ✭✭✭Special Circumstances


    jca wrote: »
    Sure does. Between the two engines my friend was stung to the guts of €1500!!

    Ah shur that's only 6months insurance.


  • #17
    jca
    Closed Accounts Posts: 8,585 ✭✭✭jca


    Special Circumstances wrote: »
    Ah shur that's only 6months insurance.

    He's in his 50's...


  • #18
    Special Circumstances
    Closed Accounts Posts: 7,569 ✭✭✭Special Circumstances


    jca wrote: »
    He's in his 50's...

    Has he looked for a quote for next year yet? :pac:


  • #19
    jca
    Closed Accounts Posts: 8,585 ✭✭✭jca


    Special Circumstances wrote: »
    Has he looked for a quote for next year yet? :pac:

    Funny you should mention that, his broker tried to look for over €700 for the coming year, up from around 400 last year. He didn't renew with them and got it from a wexford town broker for €411. My own insurance went up €90 from €345 to €435 with 123.ie.


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